From Longman Dictionary of Contemporary Englishsuperbugsu‧per‧bug /ˈsuːpəbʌɡ $ -ər-/ noun [countable] MIHBMa type of bacteria that cannot be killed by traditional drugs
Examples from the Corpus
superbug• The tots were struck down by a superbug in the intensive care unit at the London hospital.• That did kill many, but some mosquitoes became resistant: A superbug had evolved. 